Electromagnetic acoustic transducer (EMAT) has been widely used in the field of nondestructive testing due to its advantages of non-contact and designability. At present, most EMATs can only excite ultrasonic waves at a fixed frequency, which limits the application range of the transducer. To address this issue, this article proposes a new type of phase-controlled frequency-conversion EMAT (PC-FC-EMAT), which can achieve the purpose of variable-frequency excitation by adjusting the phase-control time delay of the transducer′s excitation signal. Firstly, the design scheme of PC-FC-EMAT is proposed, the frequency domain response model of PC-FCEMAT is formulated, and the mechanism of the phase-controlled time delay on the frequency domain response under the spatial response of the Lorentz force is revealed. Secondly, a multi-physics field coupling simulation model of PC-FC-EMAT is established to study the role of the phase-controlled delay on the PC-FC-EMAT time and frequency domain response, and simulate the modulation effect of the phase-controlled delay on the frequency response of PC-FC-EMAT. Finally, PC-FC-EMAT is developed, and experimental research is carried out. The experimental results show that the developed PC-FC-EMAT can achieve wavelength regulation in the range of 4~ 12 mm, and the frequency band covers 252~ 687 kHz, which meets the design requirements.